1. Field of the Invention
The present invention relates to methods and apparatuses for controlling a regulated voltage of a power-generator based on a periodic signal supplied from the outside of the power generator.
2. Description of the Related Art
Japanese Unexamined Patent Publications No, H06-276796, H06-284598, and 2002-125398 disclose one type of conventional alternators for vehicles; this type of conventional alternators has an output terminal (B terminal) located outside of the alternator casing, a ground terminal directly connected to the alternator casing, and no IG (ignition) terminals located outside of the alternator casing.
Normal alternators have a characteristic in which rotation of a rotor allows a microvoltage to be created in stator windings surrounding the rotor without the need of flow of a field current into a field winding of the rotor. Specifically, because magnetizing force remaining in the core of the rotor provides field poles therein, the rotation of the filed poles in the rotor creates magnetic fluxes so that the created magnetic fluxes induce a microvoltage in the stator windings.
A conventional alternator of this type is designed to detect the microwave induced in the stator windings, to trigger a power source circuit based on the detected microvoltage, and to turn a switch element on and off based on an operating voltage supplied from the power source circuit. The on and off control of the switch element allows an output voltage of the alternator to be regulated.
Fuel efficiency of vehicle has been improved to have low environmental impact. For example, an alternator installed in a vehicle, an input terminal mounted on the alternator housing is used to input a command signal into a control unit installed in the alternator. Based on the command signal, the control unit is operative to:
reduce a regulated voltage to reduce the output power of the alternator while the vehicle is being accelerated; and
increase the regulated voltage to store regenerative electric power in a battery.
In the type of conventional alternators disclosed in the Patent Publications, for input of the command signal output from an external control unit to the alternator control unit installed in the alternator, because no IG terminal is are located outside of the alternator casing, it is necessary to:
form an opening in the alternator casing;
additionally mount an input terminal through the opening using, for example, a connector; and
establish electrical connection between the alternator control unit and the external control unit through the input terminal.
The type of the alternator 1 however may increase the cost of the alternator because of many structural changes in the alternator and addition of parts including the connector.
Especially, let us consider that a connector connecting the input terminal is mounted in the opening formed through the rear cover of the alternator casing.
In the configuration, however, foreign particles, such as pieces of metal, particles of soil, water particles, oil particles, and the like, may enter into the alternator through the opening. This may cause the environmental resistance of the alternator to deteriorate.
Then, in order to improve the environmental resistance of the alternator to thereby ensure the reliability of the alternator of the configuration, it is necessary to provide a specific structure to the rear cover to prevent foreign particles from entering into the alternator through the opening for the input terminal. In addition, it is necessary to secure waterproof of part of the connector in which the input terminal is fitted.
As described above, mounting of the input terminal through the rear cover of an alternator using a connector may further increase the cost of the alternator.